BA TUYT CHIU GII PHNG TRNH-BT PHNG TRNH CHA CN THC (Cm nang n thi i hc!)

TG: Ng Vit Vn-o Th Hu Cc thi i hc nhng nm gn y yu cu hc sinh gii PT c cha cn thc kh phc tp, hn na nhiu hc sinh qun, yu, thiu phn kin thc phn ny. Do vy ti trnh by tng i h thng cc bn lp 12 n li, cc bn lp 10 v 11 sm lm quen v tp dt, hy vng t nhng nh hng cc bn s d dng lnh hi kin thc t cc ti liu tham kho v gio vin trn lp

( Rt gn+lu tha hai v pt+a thnh PT tch1.

iu kin

Pt

EMBED Equation.DSMT4

EMBED Equation.3

EMBED Equation.DSMT4 2. (H D 05)

S: x=3

Bin trong cn thnh BP v b khi cn c:

3.

K:

Bnh phng hai v do khng m.di th!

(Do th hai v khng m )

4. (H A 04)

S:

K, quy ng MS, c: , y l bi c bn

5. (H A 05)

S: [2; 10], Bi hai cn, bnh phng hai ln

K: x

6.

Bpt:

K:

TH1: ; Pt:

(Bnh phngdi th!)

V ,

Nn Pt VN ( khn th!)

TH2:: Pt

S: x=1

7. (D b D 06)

S: x=4; x=5, a thnh tch, nh phn tch trong cn v nhm

K:

Pt:

8. (H A 10)

S:

K: x

MS lun dng v cn nh hn 1,

Bpt:

n y dng BT BNC

hoc BP v nhm li

9. (H B 10)

S: x=5

K: ; D on nghim l 5, ta s to ra hai lin hp ng vi hai cn, sao cho c nhn t x-5, ta lm nh sau: sau khi nhn lin hp v ra PT tch c mt nhn t lun dng trn D

( Rt gn, phn tch ri t n ph10.

Ta t ta c , ta c hoc

11. (H A 02) Error! Objects cannot be created from editing field codes.

S: x=5

K:

t ,

ta c: t2-t-12=0

12. (H NT )

S: x=1

Chia TH xt. Bnh phng kt hp cc b nghch o bng cch t =t

K

Pt:

EMBED Equation.313.

K: .

Bnh phng.

t Ta c: . Vy PT c nghim

.

14. : S:

K:

t ,

Bpt:

15.

t ta c phng trnh

EMBED Equation.3

EMBED Equation.DSMT4 t=1/2

T , gii tm x ta c x=4/3

16. S:

T nhn xt HT trong cn, v n bn ngoi cn ta t u= sau bin i hp l thay vo PT.

K:

Pt:

EMBED Equation.3 (C th dng PT bc hai)

17. S: x=-24; x=41

t n ph a v HPT i xng loi 1

K:

t:

Ta c:

18.

t

Phng trnh tng ng vi h sau:

c

( Dng hm s+nh gi hai v.19.

S:

Xt hm s: f(t)=

K:

Xt hm s: f(t)= c f(t)>0

x-1>3-x hay x>2

20.

K:

VT=

Nn x=1/2 l nghim duy nht21.

Nhn xt:

Suy ra

Phng trnh c nghim

22. S: x=6

t: v bnh phng

K: x15

u+v suy ra: (u-v)20 nn:

hay x=6. Th li t/m

_1356528233.unknown

_1356784465.unknown

_1356784467.unknown

_1356784468.unknown

_1357057485.unknown

_1356784466.unknown

_1356784463.unknown

_1356784464.unknown

_1356528277.unknown

_1356784462.unknown

_1356352211.unknown

_1356352438.unknown

_1356351754.unknown

_1356351698.unknown

_1356351717.unknown